Variable compression system for internal combustion engines



y 1936- J. P. GATY I 2,040,652

VARIABLE COMPRESSION SYSTEM FOR INTERNAL COMBUSTION ENGINES I Filed March 1, 1933 5 Sheets-Sheet 1 g 1 a 14 :4 g: I

I ll J5 15 u lNVENTOR uwm/ 6,4 7') A ORNEY May 12, 1936. Y I 1 p GATY 2,040,652

VARIABLE COMPRESSION SYSTEM FOR INTVERNALCOMBUSTION ENGINES- Filed March 1, 1933 vs Sheets-Sheet 2 BY m a I gl'dRNEY y 1.936- J. P. GA1V'Y 2,040,652

VARIABLE COMPRESSION SYSTEM FOR INTERNAL COMBUSTION ENGINES Filed March 1, 1953 3 Sheets-Sheet 3 Q 72 55 p r J L x I -55 a J0 J6 o o J2 J4 J1 0 7o 0 an FL 7hr0/f/e l 0/1 e INVENTOR J0H/vP6/m A ORNEY Patented May 12, 1936 PATENT OFFICE INTERNAL COMBUSTION ENGINES John P. Gaty, New York, N. Y. Application March 1, 1933, Serial No. 659,058

16 Claims.

In the development of this art, various efiorts have been made from time-to-time to overcome the inherently low 'efliciency. of internal combustion engines at part loads, bydifierent forms of variable compression ratio devices, which, theoretically would maintain substantially; constant compression pressures atthe completion of the compression stroke, regardless of the load factor of the engine. In the earliest developments, these devices were manually operable. Later, automatic means were proposed to efiect the adjust ments necessary. All such devices however, so far as known, were lacking in mechanical simplicity and practicability from the manufacturing and servicing points of View.

' In the prior designs referred to, pistons were used as displacement means. These however, are impractical for two main reasons. Such pistons do not move except during periods when engine loads are changing, which introduces lubrication difiiculties and blow-by of gases cannot be prevented. The other reason referred to is that of the increased cost of manufactlure and maintenance. The latter can be appreciated from the fact that usually an overhead crankshaft has been provided connecting all the displacement pistons, involving greatly increased cost and additions in weight and dimensions of the engine. The objects of the present invention may be stated as being broadly to bvercome such prior objections and to provide simple, eflicient and satisfactory means for automatically adapting the compression ratio to the existing needs of the engine.

' Accordingly, the present invention differs from previous proposals, in that accurate compensation for load changes is efiected by varying the total displacement of a group of displacement devices in a multi-cylinder engine without endeavoring specifically to adjust each displacement device to the same quantitative change. Thus load changes on the engine are accompanied by accurately controlled changes in the clearance volume of the entire engine without individual control over changes in individual cylinders otherwise than by the mean effective pressure existent in such cylinders at the particular time considered. The result of this is that a cylinder having weak compression due to leaking piston rings or valves, will receive more compensation than other cyli: ders having tight valves and piston rings, the torque effort being thus smoothed out and the performance of the engine improved. This particular novel feature renders unnecessary the present close control of combustion chamber volumes in the cylinder head, machining oper ations that are very expensive due to the irregular shape of the clearance space, difficulty of measuring the volume, etc.

Thus, one of the main features of the inven- 5 tion is this control of the total compensating volume of the system of displacement devices in accordance with the load upon the entire engine and the compensation of each cylinder, according to its needas evidenced by a lack of means effective pressure in comparison with the average of the mean effective pressure of the other cylinders.

Other novel features of construction and new combinations and relations of parts constituting the invention will appear as this specification 5 proceeds.

The drawings accompanying and forming part of the specification illustrate certain practical embodiments of the invention, but it is to be understood that the structure may be modified and changed, all within the true intent and broad scope of the claims:

Fig. 1 is a diagrammatic representation of the system.

Fig. 2 is abroken sectional view across one of the cylinder heads showing a form of the invention as applied to a so-called L-head type engine.

Fig. 3 is a similar view of the invention as applied to a T-head type engine and illustrating the inter-communicating passages between cylinders as cored in the head of the engine.

Fig. 4 is a plan and broken sectional view showing details of the system outlined in Fig. 1.

Fig. 5 is an enlarged broken sectional detail of the instantaneous pressure relief valve for preventing excessive ratio adjustment upon sudden opening of the throttle valve.

Referring first to the diagrammatic layout, Fig.

1, for a, general understanding of the invention, it will be noted that the system comprises a main displacement cylinder 1, containing a piston 8, and having a noncompressible fluid, such as a suitable oil at both sides of the same. The back face of the piston. forms a movable abutment for chamber 9, to and from which fluid is added or subtracted through valve H), which is controlled by suitable means in accordance with changing load on the engine.

The rod H provides a means for the shifting of piston 8, to adjust and limit the amount of fluid in the chamber 9, in back of the piston and, conversely the amount of fluid in the chamber l2 in front of the piston. The latter communicates by a supply manifold conduit l3 and inlet check valves M, withthe several variable displacement devices l5, and these are in communication with the main supply chamber by return check valves l6 and manifolding I1.

Check valves l4 and I6 prevent fluid flowing in both directions out of the cylinder displacement devices, permitting the fluid to enter only through valves l4 and to leave through valves l6, as indicated by the arrows.

The purpose of this construction as will be observed, is to avoid intercylinder flow of fluid through short pipe lengths between cylinders and to control interchange of fluid by the mean pressure in the cylinders. The resistance to intercylinder flow is dependent upon the length'of piping or conduits and the pressure diiferential between cylinders. The length of time between pressure changes, or the explosion frequency, will govern the amount of fluid transferred from one displacement device to another, the pipe size and length and the pressure differential remaining constant. The construction shown makes it impossible for the fluid to be transferred from one device to another by means of the short paths A, B, between cylinders and requires the travel from A through the variable chamber l2 and around through inlet conduit l3, to the adjoining cylinder at point C. The return conduit l1, may be of larger size than the supply side of the system at I3, to enable the displacement devices to empty rapidly to avoid detonation from excessive pressures in the cylinders. The filling of the displacement devices instantaneously is not so necessary. The inlet side of the system therefore provides the principal force of resistance to intercylinder flow of fluid and the amount transferred from one cylinder to another during a, single engine stroke may be of inconsequential volume, even at low operating speeds. Over any reasonably short length of time, the displacement of the device in any particular cylinder will be dependent only upon the relation of the mean effective pressure therein to the mean effective pressure of the other cylinders. The cyhnder having the lowest compression receives greater compensation than the other cylinders, tending to increase its work output to approximately normal.

The main displacement piston 8, being backed by non-compressible fluid, it follows that the total displacement of the system is dependent upon the control means and is not subject to momentary fluctuation due to pressure changes during the cycle of operation of the engine. The control means herein provided are such that all conditions of operation can be properly accommodated and compensated for, distinguishing the invention from certain prior systems employing spring loaded displacement means which lack accommodation to sudden increases in load on the engine, due to inertia of the parts or dash pots placed to prevent quick changes and volume fluctuations and the fact that a constant pressure is always maintained against withdrawal of the displacement means from the combustion chamber.

In the control device herein disclosed, a special relief valve is provided to take care of sudden increases in engine load and to ,allow the cylinder pressure to act against the displacement devices with an opposing pressure, practically equal to atmospheric, instead of a. constant pressure of a much higher value, as in the case of spring loaded devices mentioned. This results in more rapid adjustment of the displacement de- Reference is now made to Figs. 2 and 3, which show the displacement devices as consisting each of a flexible diaphragm IS, in the cylinder head and forming one wall of the combustion chamber. This diaphragm is illustrated as being carried by a ring 20, seated in the head structure and as carrying a centrally disposed disc 2|, cooperating with suitable stop lugs 23, to limit movements in both directions, that is both expansive and contractive movements. For desired flexibility, the diaphragm may be corrugated as at 22, between its rigidly held rim portion and its centrally reinforced disc carrying portion. With this construction, the diaphragm is restrained in its flexing within proper limits, cannot be stressed beyond its elastic limit and the compression ratio may not increase or decrease beyond predetermined limits. When pressure is relieved back of the diaphragm by the control means for sudden load increases, the reinforcing disc may abut some part of the cylinder head such as the front of the stop lugs 23 (Figs. 2 and 3) thus preventing the diaphragm from being stressed, except on the annular mounting ring 20, which is not objectionable as such changes are of short duration.

It will be noted that the backing disc 2| of the diaphragm may be of any desired shape other than the flat form illustrated, such as concave, convex and regular or irregular outline, in accordance with any desired design of combustion space, transfer passages between valve pockets and cylinder bore,.etc., and the flexing portion of the diaphragm may be a simple annulus or other desired shape. It is noteworthy, that with this special construction, gas leakage, the construction cost is low for re sults accomplished, and the engine is not appreciably increased in physical dimensions or its appearance spoiled.

Other features to be noted by comparison of Figs. 2 and 3, are that the manifolding conduits may be either external piping as in Fig. 2 or internal cored passages in the cylinder head as in Fig. 3 and that the check valves may be either externally or internally located, in the latter instance, being accessible for repair or servicing by means of the removable plugs at 24, 25. Both styles of construction are adaptable to other than L or T-head motors, for example, to the so-called F and J-types of head construction.

To simplify explanation, Fig. 4 may be considered as a top plan view of the engine shown in Fig. 3, combined with the various elements of the control mechanism. In this view, the supply and return piping I3, II, are shown connected with the chamber I! of the main displacement cylinder through two-way valves 26, 21, connected together by a link indicated at 28, for simultaneous operation. These valves are provided as a means for enabling the refilling of the cylinder there is no possibility of' the direction of ing |1 being illustrated as actually larger than piping Hi, to permit the rapid release of the cylinder head displacement devices as heretofore recited.

One of the principal elements of the control mechanism is a so-called vacuum cylinder 29, connected with the intake manifold of the en gine by piping 38 and containing a piston 3 I, acted on by spring 32 and connected by rod 33, with one end of a floating link 34, whose opposite end is connected at 35, with piston rod When the engine is stopped and atmospheric pressure is present in the upper end of vacuum cylinder 29, spring 32 will force piston 3| downward, air below the piston being relieved through vent 36. As the position of piston 8 is maintained by the non-compressible fluid on both sides of the same, the floating link 34 will swing about the center 35 as a fulcrum. This link has connected with the intermediate portion thereof the rod 31, of the'main displacement controlling valve I8. On this valve rod are the two valve elements 38, 39, the first for cooperation with a port 40, opening into the back chamber of cylinder 1, and the second for cooperation with a port 4|, for releasing liquid from the cylinder '42, of this valve. In

this lowering movement of link 34, as valve memher 38 clears the upper edge of port 40, a way for escape of fluid in chamber 9 is opened through such port and the piping 43 to the sump 44. The release of such fluid from the 'back of the piston 8 enables the spring 45 to lift the piston, which thereby acts to withdraw fluid from the displacement devices in the motor head throughconduit l1, into chamber I2. As these displace ment devices contract to their minimum disthe order of 6 to 1.

placement'positions, no more fluid can flow and consequently piston 8 will come to rest in the course of such movements. The valve 38 has been maintained in the position close to that necessary to close the valve port 40, by-reason of the fact that as the vacuum piston 3| moves outward or downward in the illustration, the displacement piston 8 is moving upward, thus in effect compensating the valve displacement and thus holding it in the nearly closed position. Thus when the engine is stopped, the non-compressible fluid is withdrawn from the cylinder displacement devices and the engine is in effect automatically restoredto its normal compression ratio ,which, by way of example, may be on Therefore, at starting, the engine is in the condition of normal compression ratio. This is particularlyan advantage, because it is known that in prior apparatus where spring loaded displacement devices have been used, the starting under abnormally high compression ratios, such as 9 to 1 produced severe detonation,

due to full charges in the cylinders and created diflicult starting conditions.

Starting, by this apparatus, at the normal compression ratio, the engine may be idled during the usual warmingup period, in the source of which, the intake manifold vacuum rises and the pressure difiereritial between the backand front of the vacuum piston 3| increases causing the same to enter through orifice 38. This upward movement of piston rod 33 and the connected end of floating link 34 lifts-valve 38, shuttingofl escape of fluid past the upper edge of the valve and, uncovering the lower edge of valve port 40, permits fluid under pressure from a. motor driven pump 48; to pass through piping 41, into the cylinder chamber 9, which acts there to force displacement pisrise approximately as fast as the air can I II, carries the connected end of link 34down with it and, at a time when the maximum desired compression ratio has been attained, the valve port will be closed by the downward movement of valve 38, checking further ratio increasing movement of piston 8. This result can be accomplished by the provision of a stop on vacuum piston 3|, such as indicated at 18 for engagement with the lower end of the cylinder, or by the proper regulation of vacuum spring 32. The non-compressible fluid trapped in chamber 9 back to the piston 8 will then prevent any motion of this piston from minor pressure changes in the displacement system, until a change in load on the engine is accompanied by a change in the position of rod 31 of. control valve I8.

Assuming by way of further example, that after a proper warming up, increased load is placed on the engine, the consequent reduction in manifold vacuum enables spring '32 to force. down piston 3|, the connected end of floating link 34 and valve rod 31, causingfvalve element 38 to open the passage for fluid at the upper edge of port 48, which fluid then flows from the upper chamber 9, port 40 and piping 43 to the sump 44.

This relief of pressure fluid permits piston 8 to rise, which withdraws the pressure fluid or liquid from the displacement devices through piping of piston 8 will lift the floating link'34 to'shut off escape of the oil or other pressure fluid past valve element 38 to maintain a sealed system against minor pressure differences in the cylinder head displacement system. v

With a decrease in engine load and consequent increase in manifold vacuum, the vacuum piston 3| will rise, compressing spring 32, carrying upward the adjacent end of floating link 34 and valve rod 31, permitting liquid under pressure to pass for any given position of the vacuum piston 3|,

there will be a corresponding position where dis-- placement piston 8 will come to a state of equilibrium and close control valve l0, stopping fur-;

ther action. The conditions of displacement governed by piston 8 can therefore be controlled by regulation of the vacuum spring 32, and can therefore be regulated according to the'degree of vacuum in the intake manifold, which condition therefore can be made to vary inversely as the pressure at the end of the compression stroke. The compression ratio can thereforebe corrected by means of this system to take care of variations in the pressure at the end of the compression stroke and thus maintain over a reasonable period of time a constant pressure at the end of the compression stroke whatever the load on the engine.

A special feature of the control valve at II is the lower valve head 39, which serves as a balancer to compensate the pressure on the upper valve head 38, enabling the valve rod 31 to float freely and ofler very little force in opposition to .movement in either direction. From port 4|, controlled by the lower valve head 39, by-pass connection ll leads to the return line 54 to the sump 44. This by-passes the pressure fluid from pipe 41, when port ll is uncovered by lowering valve head 39, when low manifold vacuum occurs, as under fully open throttle valve operation.

In such case, the liquid pressure is not required and hence, while chamber 9 is emptying through port ll and piping 48, the pressure is also being relieved from the valve cylinder through by-pass port 4| and connections 48, 54. Such relief of pressure takes the load from the pump and conserves work of the engine. A drain 4! extends from the bottom of the valve cylinder and is connected with the by-pass preventingtrapping of liquid beneath the balancing piston valve ll. In some cases, the oil pump provided as a standard part of the engine may be used to supply pressure through the piping "and in such instances, the by-pass ll for relieving the pressure is not required nor desirable since the oil pressure should be maintained for the moving parts of the engine.

An additional special feature of the invention is the mechanism for instantaneously relieving chamber 9 of pressure when the load on the en- .gine is suddenly increased. This mechanism overcomes inherent delayed action of the vacuum cylinder and floating link mechanism, or such other control means as may be provided. If the throttle valve is suddenly opened to its full extent from a nearly closed position, the pressure rise in the engine cylinder is extremely rapid and compensation by the entire mechanism would require a measurable space of time. Because of such lag, the instantaneous pressure relief device indicated'at 50, in Fig. 4, is provided and this is coupled by linkage ll, with the throttle valve or accelerator mechanism indicated in a general way at 52. Briefly, this pressure release device serves to by-pass liquid from chamber 8, through piping I3, 54, to the sump 44, when the throttle valve is suddenly opened, automatically emptying chamber 8 sumciently to compensate for the increase in total clearance volume required by the engine to maintain approximately constant compressionratio. As chamber 9 is emptied, vacuum piston 3| is then rapidly lowered under action of spring 32, then no longer counteracted by high manifold vacuum.

For complete understanding of the sudden throttle opening instantaneous pressure release, reference is to be hadto Fig. 5, which illustrates the internal features of this mechanism. The piping ll extending from the chamber 0, above the displacement piston is of larger diameter than supply piping 41, Fig. 4, and hence capable of draining this chamber more ra can be fliled through such supply Pipe. Similarly. all parts and connections are of relatively high capacity. Chamber 5!, Fig. 5, into which pipe I opens, is subjected to the same pressure as chamber I and consequently, the relief of pressure-'inoneis accompanied by relief of pressure in the other, When the throttle valve issudthan it increase in viscosity of the fluid in into chamber 63, it causes a displacement of fluid 1 from chamber 83 to Q2, the rapidity of flow of fluid from chamber 63 into chamber 62 is governed by the restricted oriflce M in the separating wall 6|. The restriction of orifice 64 causes an increase in fluid pressure in chamber 0 and a decrease in chamber 82. The differential pressure thus produced acts upon the opposed faces of the stepped piston to resist its motion, and this resisting force may be greater than the force necessary to compress the spring I8, thus allowing plunger 51 to move within the outer plunger 50. In the relative movement of the two plungers thus effected by the delayed action of the'outer piston plunger, the ports 85, in the tubular portion of the inner plunger 51 will come into register with the ports 68, in the surrounding sleeve portion of the outer-plunger, to permit fluid to pass from chamber I, through the tubular portion 61, of the inside plunger to chamber 68, and thence to the sump by piping I4. Hence, any sudden opening of the throttle. v'alve automatically results in the release of pressure from in back of the piston in the main displacement cylinder and resultant reduction of the compression ratio, as heretofore described.

Slower opening of the throttle valve permits time for transfer of liquid from chamber 68, into chamber 62, through orifice N, enabling spring 58, to carry the stepped plunger along with the directly actuated plunger, the two then travelling along together without registering the valve ports 65, 88, so that no liquid will be released and necessary changes in displacement volume will then be effected automatically as before described in connection with Fig. 4.

The mechanism described will function at all times, no matter how suddenly the load on the enportion 80, of the outer plunger oilfers no resistance to the follow-up motion, because of the presence of a relatively large spring closed valve H, in partition I, which permits free transfer 'of liquid from chamber 6i, into chamber 88.

An opening 1! permits chamber 62 to be kept fllled from chamber 55. No change in the volume of the system through motion of plunger II occurs however, unless ports 85, 6, are brought into registry. prevents the imposition of any pressure effects on the throttle valve mechv nism that might not be desirable.

The sudden pressure release mechanism being connected in the main pressure system, it follows that any change of viscosity in the pressure liquid acts to compensatethe reaetion'of plunger It, for changes in the rest of the system. Thus, an r the system, which might cause slugglshness in compensation also causes greater resistance to motion of plungtem and to drive out all air.

iii)

er 59, at medium velocities of movement, and therefore will produce valving under less rapid changes in throttle operation, so that the device is in effect self-compensating. tending from chamber I'I back to the sump 44, provides for drainage of liquid, which mayleak past the plungers 51, 59, back to the sump.

The invention does not interfere with the usual engine servicing operations. When the cylinder head of the engine is tobe removed, it is only necessary to disconnect the two lines l3 and I! at the head. When this is done, the liquid in the displacement devices may be drained and saved. After the head is replaced and the piping again connected, the valves 26 and 21, are turned counter clock-wise in Fig. 4, so as to disconnect the supply and return pipes l3, II, from displacement cylinder I, and to connect them respectively, through said valves by piping I3, 41 with the pump and piping H with the sump 44. This puts the pump directly across the displacement devices, enabling the pump, when the engine is started, to entirely fill the cylinder head sys- To prevent any trapping of air in this portion of the system, the displacement devices may be made with sloping roof portions 15, Figs. 2 and 3, to permit all air to pass out during this refilling operation. When the system has been completely filled with liquid in this manner. the valves 26, 21, may be' returned tothe normal operating position. It will be seen from this that the invention presents no additional service problems.

The invention, it will be noted, provides a complete, practical system, readily applicable to existing engines of standard types, and operable to automatically adjust the compression ratio in accordance with changing engine loads, while permitting desirable compensation for individual cylinders and automatically prevents excessiveor undesirably high compression settings at starting or on sudden increased loading by throttle operation. The diaphragms can be sufliciently flexible to effect the necessary changes in clearance volume, being backed up by incompressible fluid which carries the actual pressure load and being protected against excessive expansion or contraction by the stop meanslimiting movements of the same. The'system also adds no appreciable bulk to the engine, is not expensive, not liable to get out of order and introduces no complications in the way of ordinary service operations about the engine.

What is claimed is:

1. A variable compression system for multicylinder internal combustion engines, comprising in combination with cylinders of a multi-cylinder internal combustion engine, liquid volume operated compression ratio adjusting displacement devices for the individual cylinders, liquid connections between the same including liquid volume displacement means for positively varying the total clearance volume of the several cylinders and intercylinder flow control means for compensating the individual cylinders to controlled flow of displacement liquid between the displacement devices of the several cylinders.

2. A variable compression system for .multicylinder internal combustion engines, comprising 1 in combination with cylinders of a multi-cylinder internal combustion engine, liquid volume operated compression ratio adjusting displacement devices for the individual'cylinders'liquid' connections between the same including liquid vol- A line 16, ex-

ume displacement means for positively varying the total clearance volume of the several cylin-. ders, intercylinder flow control means for compensating the individual cylinders to controlled flow of displacement liquid between the displacement devicesof the several cylinders, said latter means consisting of flow throttling means in the connections aforesaid.

3. Variable compression means for multicylinder combustion engines, comprising in combination with the cylinders of a multicylinder combustion engine, independently operable liquid actuated clearance volume adjusting displacement devices for the several cylinders of the engine, integrating clearance volume adjusting mechanism connected with said displacement devices, means for effecting control of saidintegrating clearance volume adjusting mechanism and flow regulating control means enabling individual adjustment of the displacement devices of the several cylinders of the engine.

4. A variable compression system for multicylinder internal combustion engines, comprising in combination with the cylinders of a multicylinder internal combustion engine, liquid actuated displacement devices for the individual cylinders of theengine, an integrating clearance volume determining device and connections between the latter and the individual displacement devices including means enabling self-adjustment of the cylinder displacement devices independently of each other, but subject to the general control of the integrating clearance volume adjusting device.

5. A variable. compression system for multicylinder internal combustion engines, comprising in combination with the cylinders of. a multicylinder internal combustion engine, liquid actuated displacement devices for the individual cylinders or the engine, an integrating clearance volume determining device, connections between the latter and the individual displacement devices including means enabling self-adjustment ofthe cylinder displacement devices independently of each other, but subject to the general control of the integrating clearance volume adjusting device and engine controlled means for setting said integrating clearance volume determining device, said .device including a piston for varying the volume of liquid back of all the displacement devices for the individual cylinders and the engine controlled means having an operating connection with said piston.

6. In combination, a multicylinder internal combustion engine, liquid actuated displacement devices in the cylinders of said engine, an integrating clearance volume determining device and supply and return conduit connections from said latter device to said displacement devices and one of said conduits being restricted as compared with the other to enable compensation as between She displacement devices of the individual cyliners.

7. In combination with a multicylinder interna combustion engine, clearance volume controlling diaphragms sealed in the heads of the individual cylinders, liquid supply) and return conduitsin.

communication with the displacement dia-v phragms of the different cylinders, anintegrating clearance volume determining displacement device and .engine controlled mechanism governing operation ofsaid integrating clearance volume determining device.

8. In combination with a multicylinder internal erning operation of the same, clearance volume controlling diaphragms sealed in the heads of the individual cylinders, liquid supply and return conduits in communication with the displacement diaphragms of the different cylinders, an integrating clearance volume determining displacement device in communication with said supplyand return conduits and means controlled by adjustment of said throttle valve for. operating said integrating clearance volume determining device.

9. In combination with an internal combustion multicylinder engine, a fluid actuated displacement device in each cylinder of the same, means for supplying non-compressible fluid to each of said displacement devices and means for effecting displacement "of all air from the supply of noncompressible fluid to the displacement device including connections providing a circuit for temporary circulation of non-compressible fluid through all the several displacement devices and an air separating chamber in said connections.

10. In combination, an internal combustion engine, a liquid actuated displacement device in the cylinder of the same, a pressure liquid supply system connected with said displacement device and including a variable displacement chamber consisting of cylinder and a piston therein, a valve controlling liquid pressure for operating said piston, a second cylinder and piston subjected to manifold pressure of the engine and a floating link connection between said pistons and said valve.

11. A multicylinder internal combustion en-' gine having intake manifold and throttle valve mechanism, liquid pressure ac ted di p ment devices in the cylinders of said engine, a main displacement device and liquid pressure connection from the same to said cylinder displacement devices and a quick acting pressure relief device actuatable by said throttle valve mechanism and comprising valving means automatically operable to vent liquid pressure from said main displacement device upon sudden throttle valve opening movements- 12. A multicylinder internal combustion engine having intake manifold and throttle valve mechanism, liquid pressure actuated displacement devices in the cylinders of said engine, a main displacement device and liquid pressure connection from the same to said cylinder displacement devices, a quick acting pressure relief device actuatable by said throttle valve mechanism and comprising valving means automatically operable I to vent liquid pressure from said main displacement device upon sudden throttle valve opening movements and a vacuum cylinder and piston connected'with the intake manifold and operable plying non-compressible fluid in back of said diaphragms, means for releasing non-compressible fluid from in back of the diaphragms, said release means operating faster than said supply means and means common to both said supply means and to said release means for arbitrarily governing the total volume of all the non-compressible fluid in back of the diaphragms.

14. In combination, a multicylinder internal combustion engine, pressure actuated displacement devices in the individual cylinders of said engine, liquid supply and return manifolds connected with said displacement devices of the individual cylinders, a variable liquid supply source common to both supply and return manifolds, one way valves opening from the return manifold to the displacement devices of the individual cylinders and one way valves opening from the ment devices in the individual cylinders of said engine, liquid supply and return manifolds connected with said displacement devices of the individual cylinders, a variable liquid supply source common to both supply and return manifolds, one way valves opening from the return manifold to ,the displacement devices of the individual cylinders, one way valves opening from the displacement devices 01' the individual cylinders to the return manifold, said return manifold being larger than the supply manifold to rapidly release the displacement liquid-from the cylinder displacement devices and means connected with said return manifold for suddenly relieving pressure therein.

16. In combination, a multicylinder internal combustion engine, clearance volume determining ders of the engine;

JOHN P. GATY. 

